You can run two tasks in parallel if you set them to run at the same time, however it depends on what the scripts are performing on if that would be a proper use of the task manager. What are each script doing?

You can try to explore on the upsShell.exe utility that can be used to run FDM scripts (refer to the doc: http://docs.oracle.com/cd/E12825_01/epm.111/readme/fdm_11112_readme.htm#_Toc231872245). After that, this can be easily scheduled, parallel/simultaneous/1 job after another, either using Windows scheduler, or other scheduling program.